This invention relates to a method of determining, by means of thermal extraction, the fat, moisture, and protein content of meat samples, and more particularly to a method of analyzing salted meat samples to which acid has been added. This application is related to copending application Ser. No. 080,802, filed Oct. 1, 1979, entitled "Method and Apparatus for Analysis of Meat Products" and Ser. No. 080,803, filed Oct. 1, 1979 entitled "Magnetic Coupling for a Weighing Balance Assembly," both filed on even date herewith and assigned to the assignee of the present invention.
In meat products which are intended for human consumption and which are comminuted during processing, the problems of accurate control of fat and/or moisture content arises. Typical of such meat products are ground beef, pork, veal and lamb, pork sausage, and blended meat products such as bologna, weiners, and liverwurst. In preparing these products, the usual procedure is to feed chunk meat into a grinder and then into a mixer where the meat and fat portions of the product are blended together.
Meat protein, as do many food proteins, has the ability to combine with fats to form a solid emulsion. That is, the protein will bind with fats to form a physically and chemically stable matrix. This phenomenon is a necessary element in the production of many important food products such as salad dressings, mayonnaise, bologna, and weiners. There are several important variables which affect the stability and strength of such emulsions. Among these are the temperature at which the emulsion is formed, the amount of work (mixing) done in blending the components, and the presence of one or more emulsifying agents.
In the production of blended meat products such as bologna, salt is added to the meat as an emulsifying aid which solubilizes the protein in the meat and allows it to encapsulate the fat particles. This results in a more stable product, and this stability persists even upon exposure of the product to thermal energy (i.e., heating or cooking).
The temperature at which the emulsion is formed also has some effect on its stability. For example, in the production of a beef and pork bologna, it has been found that a more stable product is produced if it is initially comminuted at a temperature between 50.degree. and 60.degree. F. A product formed, for example, at 40.degree. F. will exhibit small pockets of separated fat and gelatin (protein) during cooking and will lose a greater percentage of its overall fat and moisture during heating than a product which was initially formed at 50.degree.-60.degree. F.
Likewise, the amount of work (mixing) performed on a blended meat product will have an effect on the stability of the emulsion which is formed. Not unexpectedly, for typical processing operation the greater the amount of work performed in forming the product, the more stable the emulsion which is formed.
As can be seen, several factors can affect the respective amounts of fat and moisture a meat sample will lose during heating. In meat analysis processes which utilize heat to vaporize moisture and render fat as a liquid from a sample such as the processes disclosued in Davis et al, U.S. Pat. No. No. 3,916,670, and in the above-mentioned related copending applications, all of the above-discussed factors will affect the results obtained and make accurate calibration impossible. Although the amount of work performed on a sample and the temperature at which it is prepared can be controlled for fresh meat samples, the addition of varying amounts of salt to blended meats substantially increases the fat binding capabilities of the meat proteins. Thermal energy alone will not overcome this effect. As can be seen, the need exists in the art for a method of analysis in which the physical and chemical state of a salted meat sample to be analyzed can be controlled so that fast, accurate, and reproducible results can be obtained on a variety of meat samples.